Average daily light interception determines leaf water use efficiency among different canopy locations in grapevine

In Mediterranean areas grapevine water use efficiency (WUE) is becoming an important issue as grapevine production and quality are largely dependent on irrigation, and given the large area of this crop in this region. Under semi-arid conditions, grapevine water consumption rises up to 700 mm/year (rainfall plus irrigation), thus great water amounts are needed for areas typically characterised by water scarcity during grapevine growing season. Therefore, improving WUE is a challenge to secure agriculture sustainability of viticulture in these areas. In the present work we evaluate the variation of leaf WUE over time (diurnal time) and space (at eight canopy positions) under irrigation, moderate and severe water stress in field-grown Tempranillo grapevines.